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Determinants of Personal Exposure to Some Carcinogenic Substances and Nitrogen Dioxide Among the General Population in Five Swed

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Determinants of Personal Exposure to Some Carcinogenic Substances and Nitrogen Dioxide Among the General Population in Five Swed Journal of Exposure Science and Environmental Epidemiology (2014) 24, 437–443 & 2014 Nature America, Inc. All rights reserved 1559-0631/14 www.nature.com/jes ORIGINAL ARTICLE Determinants of personal exposure to some carcinogenic substances and nitrogen dioxide among the general population in five Swedish cities Annika Hagenbjo¨ rk-Gustafsson1, Andreas Tornevi1, Eva M. Andersson2, Sandra Johannesson2, Tom Bellander3, Anne-Sophie Merritt3, Ha˚kan Tinnerberg4,Ha˚kan Westberg5,6, Bertil Forsberg1 and Gerd Sallsten2 Environmental levels of airborne carcinogenic and related substances are comparatively better known than individual exposure and its determinants. We report on a personal monitoring program involving five Swedish urban populations. The aim of the program was to investigate personal exposure to benzene, 1,3-butadiene, formaldehyde, and nitrogen dioxide (NO2). The measurements were performed among 40 inhabitants during seven consecutive days, in one urban area each year, during 2000–2008. The estimated population exposure levels were 1.95 mg/m3 for benzene, 0.56 mg/m3 for 1,3-butadiene, 19.4 mg/m3 for formaldehyde, 3 and 14.1 mg/m for NO2. Statistical analysis using a mixed-effects model revealed that time spent in traffic and time outdoors contributed to benzene and 1,3- butadiene exposure. For benzene, refueling a car was an additional determinant influencing the exposure level. Smoking or environmental tobacco smoke were significant determinants of exposure to NO2, benzene, and 1, 3-butadiene. Those with a gas stove had higher NO2 exposure. Living in a single-family house increased the exposure to formaldehyde significantly. In a variance component model, the between-subject variance dominated for 1,3-butadiene and formaldehyde, whereas the between-city variance dominated for NO2. For benzene, the between-subject and between-cities variances were similar. Journal of Exposure Science and Environmental Epidemiology (2014) 24, 437–443; doi:10.1038/jes.2013.57; published online 25 September 2013 Keywords: personal exposure; benzene; 1,3-butadiene; nitrogen dioxide; formaldehyde; mixed models INTRODUCTION indoor environments, personal activity patterns and emission from 6–8 Urban populations are exposed to complex mixtures of air indoor sources. The relation between these estimates and pollutants. A large part of these compounds originate from measured individual exposure may thus be weak and therefore 9 combustion, for example, in motorized traffic, and some of these add exposure misclassification. An important alternative method are known carcinogens.1 of estimating population exposure is therefore to perform personal Ideally, epidemiological studies of carcinogenic effects of urban measurements. Personal measurements could also serve as an air pollution would be based on life-time individual inhalation important tool for validation of exposure assessment made by a exposure to all carcinogenic (and co-carcinogenic) compounds in combination of models and geographical information. urban air. This is practically not feasible. Population-based studies, Consequently, the Swedish Environmental Protection Agency therefore, typically rely on estimates of levels of specific compounds has taken an initiative to collect data on personal exposure for in selected locations. Compounds that are commonly chosen for some common air pollutants: benzene, 1,3-butadiene, formalde- such studies include, for example, benzene, 1,3-butadiene, and hyde, and NO2. The survey is conducted every year according to a formaldehyde2 as well as other compounds or metrics that relate to rotating study plan, in one of five selected urban areas. certain source types. The concentration of nitrogen oxides (NOx)or The aims of the present study are: nitrogen dioxide (NO2) is often used as an indicator of motor vehicle exhaust, including diesel engine exhaust, classified as To evaluate the environmental exposure of the adult popula- carcinogenic by IARC.3 Individual or population long-term exposure tion, aged 20–50 years, to benzene, 1,3-butadiene, formalde- is typically estimated by modeling of outdoor levels at place of hyde, and NO2, with regard to average levels as well as variation residence,4 either by land-use regression or dispersion modeling.5 within and between individuals from 2000 to 2008. Short-term exposure is often evaluated using fixed-site monitoring To assess the contribution of smoking, environmental tobacco data. In addition to the methodological uncertainties of these smoke (ETS), time spent in traffic, refueling of vehicles, and methods, they omit the contribution of infiltration of outdoor air to additional potential sources of personal exposure. 1Occupational and Environmental Medicine, Umea University, Umeå, Sweden; 2Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, Box 41, Gothenburg, Sweden; 3Centre of Occupational and Environmental Medicine, Stockholm County Council and Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; 4Department of Occupational and Environmental Medicine, Lund University, Lund, Sweden; 5Man-Technology-Environment (MTM) Research Centre, O¨ rebro University, O¨ rebro, Sweden and 6Department of Occupational and Environmental Medicine, Orebro University Hospital, Orebro, Sweden. Correspondence to: Annika Hagenbjo¨rk Gustafsson, Occupational and Environmental Medicine, Umeå University, Umeå SE-901 87, Sweden. Tel.: þ 46 90 785 37 82. Fax: þ 46 90 785 24 56. E-mail: [email protected]. Received 17 April 2013; revised 26 June 2013; accepted 3 July 2013; published online 25 September 2013 Determinants of personal exposure to carcinogenic substances and NO2 Hagenbjo¨rk-Gustafsson et al 438 METHODS From 2007 onwards, the Ogawa sampler (Ogawa & Company, Pompano Study Areas Beach, FL, USA) was used instead. The triethanolamine-coated collection filters were obtained from the manufacturer (Ogawa). The uptake rate is The five cities enrolled in the study were Stockholm, Gothenburg, Malmo¨, 8.60 ml/min (±17.6%), and the detection limit is 0.081 mg/m3 for 7 days of Umeå, and Lindesberg. Stockholm, Gothenburg, and Malmo¨ were chosen, 12 as they are the three largest cities in Sweden. Umeå is the largest city in measurements of NO2. For both NO2 measuring methods, one filter was the northern part of Sweden, and Lindesberg represents a small city in the used for the whole 7-day measurement. inner parts of the country with frequent wood burning (Supplementary Table 1, Supplementary Information). This study incorporates measure- Benzene and 1,3-butadiene. In the first measurement campaign (2000), ments from eight measurement campaigns (Supplementary Table 2). benzene was collected using Perkin Elmer samplers packed with 300 mg Tenax TA. The uptake rate of the sampler is 0.42 ml/min. As from the 2001 campaign, diffusive sampling of benzene and 1,3-butadiene was Study Participant Recruitment performed using Perkin Elmer tubes packed with Carbopack X, 60/80 In each city, a randomized selection of about 150 persons, aged 20–50 mesh (Supelco, Bellafonte, PA, USA), in order to also measure 1,3- years, was made from the Swedish population registry. An invitation letter butadiene.13 During sampling, the tubes were equipped with Perkin Elmer to participate in the study was sent to the selected persons; about 30–50 diffusion caps. The uptake rate is 0.59 ml/min (±12.5%) for benzene and letters were sent at a time. Persons who had moved were excluded, and 0.56 ml/min (±10.0%) for 1,3-butadien.14,15 The analysis was performed by the remaining persons were contacted by telephone. This procedure was automatic thermal desorption coupled with capillary gas chromatography, repeated until 40 persons had accepted to participate. In the campaigns in and identification with mass spectrometry.14 Stockholm 2003, Malmo¨ 2003, and Lindesberg 2005, invitation letters with a ‘‘yes’’ or ‘‘no’’ answer sheet and a return envelope were sent out Formaldehyde. During the first two measurement campaigns (2000 and together. In Stockholm, invitation letters were sent to all of the randomized 2001), formaldehyde was collected using a modified GMD 570 Series persons at the same time, and after 3 weeks, a reminder letter was sent. Formaldehyde Dosimeter badge (GMD Systems, Hendersonville, PA, The mean response rate was 59% (Gothenburg, 2000: 71%; Umeå, 2001: USA).16 The sampler consists of a polypropylene housing and two glass- 67%; Stockholm, 2003: 44%; Malmo¨, 2003: 43%; Lindesberg, 2005: 42%; fiber filters impregnated with 2,4-dinitrophenyl-hydrazine (2,4-DNPH). The Gothenburg, 2006: 60%; Umeå, 2007: 81%; Malmo¨, 2008: 66%). standard sampler with 0.7 mg of 2,4-DNPH/filter was modified by adding an extra amount of reagent (3.5 mg DNPH/filter) to the filter to make it last Participant Activities and Questionnaires for 7 days of measurements. The uptake rate of the sampler is 20.5 ml/min (±8.6%).17 Formaldehyde was analyzed by high-performance liquid A questionnaire was distributed at the start of the measurements including chromatography with UV detection at 365 nm.16 The detection limit of questions about home characteristics (type of house, heating system, the method is 0.1 mg/sample, which corresponds to a detection limit of access to a gas stove indoors, if a garage was attached to the house), 0.5 mg/m3 for 7 days of measurements.17 smoking habits, occupation, work address, commuting, means of From 2003 to 2008, the UMEx100 sampler (SKC, Eighty Four, PA, USA) conveyance,
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